General Information: The Asian Clam, scientifically known as the Corbicula Fluminea, is a freshwater bivalve with a relatively brown or yellowish-gold exterior, and a white or purple interior. It rarely grows larger than 1.5 inches. It has rows of elevated ridges on the exterior of the hell. It’s native to temperate and tropical climates in southern Asia and east to the Mediterranean, Southeast Asian island, eastern and central regions of Australia, and some places in Africa. (1)
Corbicula Fluminea
size and coloring
Detailed Description: An Asian Clam reproduces by means of self-fertilization. This means the clam generates both egg and sperm. While it is self-fertilizing it will also release sperm into the water so that other clams may obtain it and fertilize their eggs. Just one 1.5 inch clam can produce up to 400 larvae per day or 70,000 annually! (1) The lifespan of an Asian Clam can last from one year of age, to seven. (2) But just during a life-span of four years they are believed to be producing about 100,000 new clams! (3). The Asian Clam is a filter feeder, which means it produces its own food by using an inhalant siphon (tube-like structure in mollusks that allows liquid to enter and leave the body) to draw in water, food, and dissolved oxygen. It then uses an exhalant siphon to release water and waste. No source is very clear on why Asian Clams seems to out compete the native species in an area, but it might be because of the fact that the Asian Clam can reach high densities of about 10,000 to 20,000 clams per square inch in a very short amount of time. (1) Scientists believe that the calcium released from the dead clams attract zebra mussels, another invasive species, which take over the clam beds and feed off the calcium. Also the two liters of water filtered through the Asian clams are thought to have brought algae to Lake Tahoe. (Youtube video). They also fear that because they are so well hidden into their sandy burrows that they will consume so much plankton, the native fish will starve. (3)
Clams covering lake's bottom
Habitat: The Asian Clam originated from southern Asia and east to the Mediterranean, Southeast Asian islands, eastern and central regions of Australia, and some places in Africa. It is considered a freshwater species, dwelling in waters in areas of temperate or tropical climate. The species does not do well in waters below 36 degrees Fahrenheit but reproduces well in areas with waters above 61 degrees Fahrenheit. Although it is a freshwater species, it can live in slightly brackish waters (depending on how high salinity is). (1) They tunnel in the mud and can live from the shoreline all the way up to 140 feet underwater!(3)
Distributions: They believe the Asian clam originally was brought here by Chinese immigrants as a source of food. The invasive species was allegedly first spotted in 1924 on the west coast, but in 1937 it was officially discovered in the Columbia River in Washington. In the 1970s the clam had spread across the Mississippi Basin, the Gulf Coast, and the east coast. In the 1990s it had hit New Jersey, New York, Delaware, and Connecticut. It is extremely popular in Indiana now, and has spread itself not only throughout the District of Columbia but also 41 of the 50 United States.(1) The states being: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, and Wisconsin.(2)
amount of asian clams across the U.S.
Impacts on the Ecosystem: The effect the Asian clam has on the ecosystem is mostly negative. Because it reproduces in great quantities it takes away a lot of limited food resources for the native species that live there.(1) Not to mention it attracts other invasive species when it dies and releases the calcium. However, because the species has come to many waterways in the United States in great quantities, some native fish have adjusted their diet to feed on the Asian clams.(2) The most well-known effect it has had on the ecosystem is “biofouling”. Biofoulingis the harming of something due to the escalation or actions of a living organism. As a result of rising quantities of the Asian clam, many power plants, drinking water treatment systems, and other industries that withdrew water have suffered.(1) The clams have also done damage to irrigation system and pipes.(2)
Impacts on Humans: Economically, Asian clams have a very strong effect on humans. Because they rise to such great quantities and have caused so much damage to the pipes used in power and water industries, the government has contributed millions of dollars to fix these damages. It is estimated that it takes about a billion U.S. dollars annually to remove the large amounts of clams (both living and dead) that are clogging up the pipes. Recently in the United States, several nuclear reactors had to be shut down (temporarily) while they cleared out the Asian clams that had invaded the cooling systems. The clams move with water currents and generally end up getting sucked into generating facilities where they then attach themselves to the walls and obstruct water flow. In Tennessee and Ohio, the gravel and sand in the riverbeds are used to make cement. The clams get mixed into the cement and burrow themselves to the surface just as the cement sets, which ends up weakening the structure. So although there are no health impacts, the economic impacts are very high. (2)
Control Measures: Because the severity of Asian clam invasions has gotten so bad, many actions are being taken to eliminate these pests. In some places there are laws in which it is said to be illegal to import, transport, or acquire this species in order to regulate the spreading of them. Many scientists (like the ones in the video below) have resulted to smothering the clams and then clearing and disposing of their dead bodies. Others use screens to filter out the clams from water systems. Chemicals like chlorine and bromine, although have been proven to kill these creatures, are prohibited in most places as a form of pesticide. Hot water injected into pipes where the clams have taken over, is another way people can kill off the invaders. Some ways scientists suggest that civilians can get involved is by educating themselves on this species, and learning of ways to prevent them from entering our waterways. Some suggestions are: “Never empty your bait bucket into a different body of water from where you obtained your bait. Dispose of unused bait in the trash; never transfer live fish from one body of water to another; removed all plant fragments and rinse any mud or debris from equipment and wading gear before leaving the access area; and drain all water from your boat before leaving the launch site.” The costs of these preventions are not mentioned in any of my sources. (1)
The Asian Clam, scientifically known as the Corbicula Fluminea, is a freshwater bivalve with a relatively brown or yellowish-gold exterior, and a white or purple interior. It rarely grows larger than 1.5 inches. It has rows of elevated ridges on the exterior of the hell. It’s native to temperate and tropical climates in southern Asia and east to the Mediterranean, Southeast Asian island, eastern and central regions of Australia, and some places in Africa. (1)
Detailed Description:
An Asian Clam reproduces by means of self-fertilization. This means the clam generates both egg and sperm. While it is self-fertilizing it will also release sperm into the water so that other clams may obtain it and fertilize their eggs. Just one 1.5 inch clam can produce up to 400 larvae per day or 70,000 annually! (1) The lifespan of an Asian Clam can last from one year of age, to seven. (2) But just during a life-span of four years they are believed to be producing about 100,000 new clams! (3). The Asian Clam is a filter feeder, which means it produces its own food by using an inhalant siphon (tube-like structure in mollusks that allows liquid to enter and leave the body) to draw in water, food, and dissolved oxygen. It then uses an exhalant siphon to release water and waste. No source is very clear on why Asian Clams seems to out compete the native species in an area, but it might be because of the fact that the Asian Clam can reach high densities of about 10,000 to 20,000 clams per square inch in a very short amount of time. (1) Scientists believe that the calcium released from the dead clams attract zebra mussels, another invasive species, which take over the clam beds and feed off the calcium. Also the two liters of water filtered through the Asian clams are thought to have brought algae to Lake Tahoe. (Youtube video). They also fear that because they are so well hidden into their sandy burrows that they will consume so much plankton, the native fish will starve. (3)
Habitat:
The Asian Clam originated from southern Asia and east to the Mediterranean, Southeast Asian islands, eastern and central regions of Australia, and some places in Africa. It is considered a freshwater species, dwelling in waters in areas of temperate or tropical climate. The species does not do well in waters below 36 degrees Fahrenheit but reproduces well in areas with waters above 61 degrees Fahrenheit. Although it is a freshwater species, it can live in slightly brackish waters (depending on how high salinity is). (1) They tunnel in the mud and can live from the shoreline all the way up to 140 feet underwater!(3)
Distributions:
They believe the Asian clam originally was brought here by Chinese immigrants as a source of food. The invasive species was allegedly first spotted in 1924 on the west coast, but in 1937 it was officially discovered in the Columbia River in Washington. In the 1970s the clam had spread across the Mississippi Basin, the Gulf Coast, and the east coast. In the 1990s it had hit New Jersey, New York, Delaware, and Connecticut. It is extremely popular in Indiana now, and has spread itself not only throughout the District of Columbia but also 41 of the 50 United States.(1) The states being: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, and Wisconsin.(2)
Impacts on the Ecosystem:
The effect the Asian clam has on the ecosystem is mostly negative. Because it reproduces in great quantities it takes away a lot of limited food resources for the native species that live there.(1) Not to mention it attracts other invasive species when it dies and releases the calcium. However, because the species has come to many waterways in the United States in great quantities, some native fish have adjusted their diet to feed on the Asian clams.(2) The most well-known effect it has had on the ecosystem is “biofouling”. Biofouling is the harming of something due to the escalation or actions of a living organism. As a result of rising quantities of the Asian clam, many power plants, drinking water treatment systems, and other industries that withdrew water have suffered.(1) The clams have also done damage to irrigation system and pipes.(2)
Impacts on Humans:
Economically, Asian clams have a very strong effect on humans. Because they rise to such great quantities and have caused so much damage to the pipes used in power and water industries, the government has contributed millions of dollars to fix these damages. It is estimated that it takes about a billion U.S. dollars annually to remove the large amounts of clams (both living and dead) that are clogging up the pipes. Recently in the United States, several nuclear reactors had to be shut down (temporarily) while they cleared out the Asian clams that had invaded the cooling systems. The clams move with water currents and generally end up getting sucked into generating facilities where they then attach themselves to the walls and obstruct water flow. In Tennessee and Ohio, the gravel and sand in the riverbeds are used to make cement. The clams get mixed into the cement and burrow themselves to the surface just as the cement sets, which ends up weakening the structure. So although there are no health impacts, the economic impacts are very high. (2)
Control Measures:
Because the severity of Asian clam invasions has gotten so bad, many actions are being taken to eliminate these pests. In some places there are laws in which it is said to be illegal to import, transport, or acquire this species in order to regulate the spreading of them. Many scientists (like the ones in the video below) have resulted to smothering the clams and then clearing and disposing of their dead bodies. Others use screens to filter out the clams from water systems. Chemicals like chlorine and bromine, although have been proven to kill these creatures, are prohibited in most places as a form of pesticide. Hot water injected into pipes where the clams have taken over, is another way people can kill off the invaders. Some ways scientists suggest that civilians can get involved is by educating themselves on this species, and learning of ways to prevent them from entering our waterways. Some suggestions are: “Never empty your bait bucket into a different body of water from where you obtained your bait. Dispose of unused bait in the trash; never transfer live fish from one body of water to another; removed all plant fragments and rinse any mud or debris from equipment and wading gear before leaving the access area; and drain all water from your boat before leaving the launch site.” The costs of these preventions are not mentioned in any of my sources. (1)
Works Cited:
1) Aquative Invasive Species. "Asiatic Clam." Editorial. The Offical Website of the State of
Indiana(IN.gov). Governor Mitch Daniels, Apr. 2009. Web. 14 Dec. 2009.
<http://www.in.gov/dnr/files/Asiatic_Clam.pdf>.
2) NAS- Nonindigenous Aquatic Species. "Corbicula Fluminea." Editorial. USGS. Pam Fuller, 7 May 2009.
Web. 14 Dec. 2009. <http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=92>.
3) “Tiny Asian clams invade Lake Tahoe.” UPI NewsTrack. (August 19, 2009): NA. Student Resource Center – Gold. Gale. Stroudsburg High School. 4 Dec. 2009 <http://find.galegroup.com/srcx/infomark.do?&contentSet=IAC-1&docId=A206132458&source=gale&srcprod=SRCG&userGroupName=stro53037&version=1.0>